From: Bjørn Mork <bjorn@xxxxxxx> The probe does not strictly require the USB_CDC_DMM_TYPE descriptor, which is a good thing as it makes the driver usable on non-conforming interfaces. A user could e.g. bind to it to a CDC ECM interface by using the new_id and bind sysfs files. But this would fail with a 0 buffer length due to the missing descriptor. Fix by defining a reasonable fallback size: The minimum device receive buffer size required by the CDC WMC standard, revision 1.1 Signed-off-by: Bjørn Mork <bjorn@xxxxxxx> Cc: stable <stable@xxxxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx> --- drivers/usb/class/cdc-wdm.c | 4 +++- 1 files changed, 3 insertions(+), 1 deletions(-) diff --git a/drivers/usb/class/cdc-wdm.c b/drivers/usb/class/cdc-wdm.c index a940ad9..d2b3cff 100644 --- a/drivers/usb/class/cdc-wdm.c +++ b/drivers/usb/class/cdc-wdm.c @@ -57,6 +57,8 @@ MODULE_DEVICE_TABLE (usb, wdm_ids); #define WDM_MAX 16 +/* CDC-WMC r1.1 requires wMaxCommand to be "at least 256 decimal (0x100)" */ +#define WDM_DEFAULT_BUFSIZE 256 static DEFINE_MUTEX(wdm_mutex); @@ -636,7 +638,7 @@ static int wdm_probe(struct usb_interface *intf, const struct usb_device_id *id) struct usb_cdc_dmm_desc *dmhd; u8 *buffer = intf->altsetting->extra; int buflen = intf->altsetting->extralen; - u16 maxcom = 0; + u16 maxcom = WDM_DEFAULT_BUFSIZE; if (!buffer) goto out; -- 1.7.8.3 -- To unsubscribe from this list: send the line "unsubscribe linux-usb" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
